1. Field of the Invention
The present invention relates to a method of quantitatively determining the amount of functional groups of a polymer particle having functional groups that can be used favorably in applications such as a carrier for diagnostic and pharmaceutical products, a carrier for chromatography, a viscosity adjuster, a resin molding material, a paint additive, a crosslinking/hardening agent, and a cosmetic additive, and in particular to a method of quantitatively determining the amount of functional groups of a polymer particle having maleimidyl groups as the functional groups.
2. Description of the Related Art
Polymer particles having a particle diameter in the range of approximately 0.01 to 100 μm have been used favorably in such applications as a carrier for diagnostic and pharmaceutical products, a carrier for chromatography, a carrier for combinatorial chemistry, a viscosity adjuster, a resin molding material, a paint additive, a crosslinking/hardening agent, and a cosmetic additive, and it is important to determine the amount of functional groups quantitatively for control of the properties of the particles.
Conventional quantitative methods of determining the amount of functional groups of a polymer particle include, for example, a method of determining the acid value and the hydroxyl value of a polymer as specified in Japanese Industrial Standard (JIS) K0070 and a method of determining the amount of amino groups of a plastic material as specified in JIS K7245. These methods, which are intended for use in analysis of general polymeric materials, need a large amount of a sample, a long period of time, and many steps of procedures for analysis. In addition, Journal Soc. Syn. Org. Chem. Vol. 60, No. 5, pp. 454 to 463 discloses analysis of the absorption peaks obtained by infrared spectroscopic analysis of a particle surface and ultraviolet and visible light analysis that determines the degree of reaction between a particle and a reagent by comparison with that determined in a blank test as methods for determining the amount of functional groups of a particle. In these analytical methods which do not determine the amount of functional groups directly, the particles having the same amount of functional groups often differ in actual properties and the values obtained often vary significantly depending on the surface state of the samples.
A method of determining the amount of maleimidyl groups is disclosed in the General Catalog of Dojindo Laboratories, 23rd Ed., pp. 80 and 81. The method, which is intended for use in analysis of general compounds, needs a large amount of a sample, a long period of time, and many steps of procedures for analysis, similar to the methods of determining functional groups above.
On the other hand, a flow cytometer is an instrument that analyzes the fluorescence intensity, the scattering intensity, and the number of particles; and methods utilizing a flow cytometer include, for example, a method of measuring the coagulative state of latex particles described in Japanese Patent Application Laid-Open (JP-A) No. 5-107249, a quantitative method of determining the amount of a cyst of algae descried in JP-A No. 7-265096, and a quantitative method of determining the amount of phosphorus-accumulating microbes in sludge described in JP-A No. 9-252799. These methods, each of which compares the fluorescence intensity of particles qualitatively, mainly focus on counting the number of particles in analysis and thus cannot be applied to quantitative analysis of the amount of the functional groups of particles.